280 The Study of Animal Life PART iv 



briefly, for they have been stated many times of late years. 

 The idea of evolution has also justified itself by the light 

 which it has cast not only on biological, but on physical, 

 psychological, and sociological facts. There has never been 

 a more germinal idea ; it is fast becoming organic in all 

 our thinking. 



To those who feel a repugnance to the doctrine of 

 descent, I suggest the following considerations : 



(1) In so far as conclusions do not affect conduct, it 

 seems wise to conserve what makes one happiest. If your 

 intellectual and emotional necessities are better satisfied, 

 for instance, by any one of the creationist theories than 

 by that of a gradual and natural progress from simple 

 beginnings to implied ends, and if you feel that your sense 

 of the marvel, beauty, and sacredness of life would be 

 impoverished by a change of theory, then I should not seek 

 to persuade you. 



(2) But as we do not think a tree less stately because 

 we know the tiny seed from which it grew, nor any man 

 less noble because he was once a little child, so we ought 

 not to look on the world of life with eyes less full of wonder 

 or reverence, even if we feel that we know something of its 

 humble origins. 



(3) Finally, we should be careful to distinguish between 

 the doctrine of natural descent, which, to most naturalists, 

 seems a solemn fact, and the theories of evolution which 

 explain how the progressive descent was brought about. 

 For in regard to the causal, as distinguished from the modal 

 explanation of the world, we are or ought to be uncertain. 



3. Origin of Life. It is no dogma, nor yet a "law 

 of Biogenesis," but a fact of experience, to which no excep- 

 tion has been demonstrated, that living organisms arise 

 from pre-existent organisms Omne vivum e vivo. 



As to the origin of life upon the earth we know nothing, 

 but hold various opinions, (i) Thus it is believed that life 

 began independently of those natural conditions which come 

 within the ken of scientific inquirers ; in other words, it is 

 believed that the first living things were created. That 

 this belief presents intellectual difficulties to many minds 



